An Organic Light Emitting Diode (OLED) display device, as an active light emitting display device, is increasingly applied to the high-performance display field, due to its characteristics such as self-illumination, fast response, wide viewing angle and ability to be fabricated on a flexible substrate.
In a manufacturing process of the OLED, a patterned thin film layer is formed usually by using a vacuum evaporation process in combination with a mask process. As shown in FIG. 1, by using a mask 100, a red organic light emitting material 11, a green organic light emitting material 12 and a blue organic light emitting material 13 are sequentially evaporated on a surface of a substrate 10 by shifting side by side. In this procedure, a contaminant generated will be adsorbed on the mask 100, and may cause clogging of an opening of the mask 100. Thus, in the above-described shifting procedure, a defect phenomena such as a repetitive defect and uneven filming will be caused.
In the prior art, in order to solve the above-described problem of mask pollution, a mask cleaning method generally used comprises: wet liquid immersion, dry collecting, dry physical adhesion, dry plasma ashing cleaning, and so on. Therein, the dry collecting is to remove the contaminant adhered to a surface of the mask by airflow in a physical air exhaust mode; and the dry physical adhesion is to remove the contaminant adhered to the surface of the mask by using a physical or a chemical sticking board. However, in the above-described modes, it is difficult to clean a tiny and sticky contaminant in a corner or slit, and the cleaning effect thereof is limited. And the dry plasma ashing cleaning is to ash the contaminant on the surface of the mask by using high-energy plasma, and the method is capable of removing an organic contaminant and fine dust, but it is difficult to remove a larger inorganic contaminant; moreover, in an ashing procedure, the surface of the mask is likely to be damaged. In addition, the wet liquid immersion method is to remove the contaminant on the surface of the mask by using organic liquid immersion, but by using this method, liquid is apt to remain in the slit of the mask, to cause corrosion to the mask, and reduce a service life of the mask. In addition, it is further necessary to consume manpower and material resources to regularly perform maintenance on the cleaning apparatus subjected to wet liquid immersion. At the same time, in the procedure of using the method, wasted solution will be generated to pollute environment.